Module 9 Flashcards
Overview of Motor System and (L)ower (M)otor (N)eurons and Brainstem, Spinal Level Reflexes (31 cards)
True or False: In order to convert an intention into an action the motor system must go through a series of sensorimotor transformations.
True
Explanation:
This statement is true: the motor system must identify the goal and then use sensory information about objects in the environment and sensory information about the performers body position to determine the extrinsic kinematic and then convert those to intrinsic kinematics (desired joint rotations to reach the target) and then convert the intrinsic kinematics to kinetics (forces need to produce the joint rotations).
Sensory feedback used after a movement is executed will allow the system to do which of the following?
Plan movements in advance
Correct errors in a movement
Execute a movement
Correct errors in a movement
Explanation:
The motor system will monitor a movement that is being executed to make sure the intended plan is working. This sensory feedback can be used to correct the movement if errors occur and it can be used to update the motor plan for future use.
True or False: The somatic motor system allows us to plan and execute movements enabling us to interact with our environment.
True
Which type of movement produced by the somatic motor system has a context dependent association with stimuli, is modifiable and can be learned with practice?
Voluntary
Reflexive
Rhythmic
Voluntary
Explanation:
Voluntary movements involve choices between alternatives (not indicated in question stem), have a context dependent association with stimuli, are modifiable, and the can be learned with practice. Reflexive movements are movements that are made is direct response to sensory stimuli; the are involuntary and stereotyped; rhythmic movements are a special class of voluntary movements.
Which areas of the brain are part of the highest level of the motor hierarchy and are important for planning movements and sending execution commands to lower centers.
Motor cortices
Cerebellum
Spinal cord
Basal nuclei
Motor cortices
Explanation:
The motor cortices are the part of the highest level of the motor hierarchy and they will be responsible for planning and sending execution commands down to the lowest level of the hierarchy. The cerebellum will modulate motor neurons of the highest level of the hierarchy and be important for comparing and coordinating movements and for motor skill learning by trial and error. The basal nuclei will play an important role in gating motor plans: activating some and suppressing others. The spinal cord contains local circuit neurons and lower motor neurons important for conveying the final commands to skeletal muscles.
Which functional subsystem will regulate skilled limb movement allowing us to write our name on a card?
Dorsolateral
Ventromedial
Corticonuclear tract
Dorsolateral
Explanation:
The dorsolateral system will mediate skilled limb movements; the ventromedial system will mediate postural control; and the corticonuclear system will control face and oral motor movements.
True or False: Lower motor neurons are the final motor pathway, allowing a neural signal to be converted into a mechanical event.
True
Explanation:
This statement is true: lower motor neurons are the final motor pathway. The action potential of a motor neuron will cause a muscle fiber to depolarize setting off cross bridge cycling.
Where are lower motor neurons that innervate limb muscles located?
Anterior horn of the spinal cord
Trigeminal motor nucleus
Facial motor nucleus
Anterior horn of the spinal cord
Explanation:
Motor neurons that innervate the muscles of the trunk and limbs are located in the anterior horn of the spinal cord. Motor neurons that innervate muscles of the head and neck are located in the cranial nerve somatic motor nuclei (like the trigeminal and facial motor nuclei).
Which of the following neurons innervates the contractile ends of the muscle spindle?
Alpha motor neurons
Gamma motor neurons
Interneurons
Gamma motor neurons
Explanation:
Gamma motor neurons will innervate the infrafusal fiber (contractile poles of the muscle spindle) and will be important in maintaining the tension in the muscle spindle. Alpha motor neurons innervate the extrafusal fibers which are the tension generating fibers of skeletal muscle. Interneurons (local circuit) neurons will integrate sensory information from the periphery and descending control signals from higher brain regions and they will use this information to regulate the activity of the lower motor neurons.
Which neurotransmitter is released at the neuromuscular junction?
Acetycholine
Glutamate
Glycin
Acetycholine
Explanation:
Acetylcholine is the neurotransmitter released at the neuromuscular junction. It will bind the nicotinic acetylcholine receptors allowing Na+ to enter the cell resulting in the depolarization of the muscle fiber.
True or False: During voluntary movements the motor system will activate both alpha and gamma motor neurons simultaneously.
True
Explanation:
This statement is true: during voluntary movement both alpha & gamma motor neurons will be activated simultaneously. Activation of the alpha motor neuron results in muscle fiber contraction, while activation of the gamma motor neuron maintains the sensitivity of the muscle spindle during movement allowing the spindle to provide ongoing proprioceptive information.
What are the ways in which higher brain centers can modulate the activity of reflexes? Select all that apply.
They can decrease the threshold for activation of the reflex.
They can decrease the gain of a reflex
They can increase the threshold for activation of a reflex
They can increase the gain of a reflex.
They can decrease the threshold for activation of the reflex.
They can decrease the gain of a reflex
They can increase the threshold for activation of a reflex
They can increase the gain of a reflex.
(all of the above)
Explanation:
All of the above are correct: higher brain centers can alter the threshold (decreasing or increasing it) for activating the reflex or change the gain (strength of the response once activated). This allows higher centers to produce adaptive behavioral responses based on context.
During the monosynaptic stretch reflex, sensory information will activate which of the following neurons to mediate reciprocal inhibition so that the antagonist muscle will relax?
Gamma motor neurons
Alpha motor neurons
Interneuron
Interneuron
Explanation:
During the monosynaptic stretch reflex, sensory information from the muscle spindle will activate an alpha motor neuron directly causing contraction of the agonist (the same muscle that was stretch). Simultaneously, the sensory single will activate an inhibitory interneuron, which will inhibit the alpha motor neuron of the antagonist muscle (reciprocal inhibition).
The activation of gamma motor neurons by higher brain centers to increase the tension of the muscle spindle so that a small stretch of the muscle will produce a greater than typical increase in muscle tension is an example of which of the following?
Alpha-gamma co-activation
Gamma bias
Monosynaptic stretch reflex
Gamma bias
Explanation:
This is known as gamma bias. This allows the system to set the spindle for more adaptive responses.
The golgi tendon organ is the afferent limb of which of the following reflexes?
Monosynaptic stretch reflex
Autogenic inhibition reflex
Flexion withdrawal
Autogenic inhibition reflex
Explanation:
The golgi tendon organ is the sensory receptor that mediates the autogenic inhibition reflex. Muscle spindles mediate the monosynaptic stretch reflex and nociceptive information mediates the flexor withdrawal reflex.
True or False: The flexor withdrawal & flexion-crossed extension reflex involve the activation of both excitatory and inhibitory interneurons that mediate complex patterns of movement on both sides of the body.
True
Explanation:
This statement is true: this is a very complex reflex. Excitatory input from nociceptors will activate both excitatory interneurons to activate appropriate alpha motor neurons for contraction of agonists, and inhibitory interneurons to mediate reciprocal inhibition of the appropriate antagonists on both sides of the body.
Which nerve carries the afferent and efferent limbs of the jaw jerk reflex?
Facial
Trigeminal
Glossopharyngeal
Trigeminal
When the left cornea is touched this nociceptive information will typically result in the activation of which of the following?
Motor neurons in the nucleus ambiguous on the ipsilateral side
Motor neurons in the facial motor nucleus bilaterally
Motor neurons in the trigeminal motor nucleus ipsilaterally
Motor neurons in the nucleus ambiguus bilaterally
Motor neurons in the facial motor nucleus bilaterally
Explanation:
The corneal reflex has a direct (ipsilateraly) and consensual (contralateral) response. When nociceptive information traveling on the ophthalmic division of the trigeminal nerve reaches the spinal trigeminal nucleus, second order neurons of this nucleus will activate motor neurons in the facial motor nuclei bilaterally.
The pharyngeal reflex (gag reflex) will also have a direct and consensual response resulting in activation of motor neurons in the nucleus ambiguus bilaterally.
What types of movements are produced by the somatic motor systems?
What areas of the brain are considered part of the motor system?
What is the difference between serial and parallel-distributive processing?
Which subsystems control skilled limb movement, postural control, oral motor control and movements of the eye, respectively?
Where are lower motor neurons located and what is their primary function?
What is the difference between an alpha and gamma motor neuron?
